Transmission



E. E. wEMP TRANSMISSION original Filed Aug. 23, 19:59

lMay 28, 1946.

Re. 22,761 l 9 sheeis--shee1; 1

\ INVENTOR. .rnj Wemp ATTORNEY S E. E.-wl:MP Re. 22,761

l TRANSMISSION r1 inal Filed Aug. 23, 1939 9 Sheets-Sheet 2 K May 28, 1946.

INVENTOR l'rnet Z'. tf1/emp- @Mmm "gai, v

4 f, YS s l O Y ATTORNEYS May 2s, 1946. S E. E. wx-:MP Re. 22,761 j TRANSMISSION v original Filed Aug. 23. 1939 9 Sheets-sheet a ,17 jg 4b je .az 30 f6 Z3 May 28,1945 E. E. wEMP Re. 22,761

Y TRANSMISSION original Filed Aug. 23, 1959 9 sheets-sheet 4 32' fa' J6 55 .57 l l g 1529-13 AHJVENTOR. l] Ernest E, ift/emp BY wgwvf 30' ."3 f y ATTQEIEYS s E.. E. WEMP May 28, 19.46.

TRANSMISSION 9 Sheets-Sheet 5 Q2/L ATTORNEYs Original Filed Aug. 23, 1939 INVENTOR. rne l. )ft/emp May 28, 1946.

l E. E. wEMP TRANSMISSIN 9 Sheets-Sheet 6 Original Filed Aug. 23. 1939 INVENFOR Ernest E h/emp l/ A T'roRNEYs BY MM May 28, 1946. I E. E. wEMP Re 22,751

TRANSMISSION original Filed Aug. 25, 1959 9 sheets-'sheet 7 Erb-6i 17.'. emp

ATroRNEj I May- 28, 1946. 'Eg E. {NE-MP R@ 22,761

TRANSMISS ION Original Filed Aug. 25, 1939 9`Sheets-Sheet 8 I INV NTOR, Ernes? emp ,AJ'FORNEYS E. E. WEMP May 2s, 1946.

TRANSMISSION l l original Filed Aug. 2:5, 19:59 v esmas-sheet 9 Reissued May 28, 1946 TRANSlHISSION Ernest E. Wemp, Detroit, Mich., assigner of five per cent to Clyde J. Smith, five per cent to Leah Kathleen Smith, twenty per cent to Lila A. Wemp, all of Detroit, Mich., and five per cent to Eleanor May Wemp, Los Angeles, Calif.

`Original No. 2,371,564, dated March 13, 1945,

Serial No. 291,574, August 23, 1939. Application for reissue October 4, 1945, Serial No.

Thisinvention relates to means for the transmission of forces from a driving member to a driven member and also from the driven member to the driving member.

The means may be in the nature of a trans-` mission disposed somewhere in the power line between the engineand the traction wheels of a vehicle, such as an automotive vehicle. As is Well known, the torque is delivered by the engine of an automotive vehicle when the engine is driving the vehicle, and the torque is in a direction from the traction wheels to the engine at certain times, as for example, when the throttle of an engine is controlled to tend to reduce its speed. This can also betrue of other types of Vehicles and of other mechanisms.

One ofthe objects of the invention is to provide a gearing or transmission capable of establishing diiierent gear ratios between the .driving and driven members through the means of dental engagement of -certain 'of the parts. The term it in other words, the dental engagement is effected substantially zation. i

In accordance with the invention, an arrangeat the time of synchroni- -ment is provided whereby the different ratios be-v tween the driving and driven members may be effective to both change the ratio from a higher to a lower and from a lower to a higher ratio, and both by the same action of controlling the torque reversal. And this is accomplished without` breaking the power line through the means of an instrumentality such as a clutch.

The arrangement of the invention is nicely adapted to beorganized into what is commonly dental engagement is used to denote an engagement 'of teeth or similar irregularly formed elements on two or more members. vIt is also an object of the invention to provide an arrangement wherein the action of changing the gear ratio 'between the driving and driven members is obtained incident to the reversal of torque. When these two ideas or objects are combined the resultant structure may change the gear ratio between the driving and driven members through the means of a dental engagement eiectedby torque reversal. It will be seen, therefore, that in an automotive vehicle the gear ratio" between the driving and driven members may bechanged by the simple expedient of manipulating the engine throttle to cause a torque reversal.

Another object of the invention is the provision of a transmission, that is a device for 'transmitting power from one member to another,A

the provision of a gearing or transmission of this" torque reversal the parts to be brought into den tal engagement are substantially synchronized at known as a planetary type of gearing or transmission which involves a sun gear and planetary gears, although the arrangement of eiecting different ratios'upon torque reversal may be emtween the driving and driven members may or may not be made as determined by the pre-selec,- tion. A still further object of the invention is type, in which the control is not only subject to torque reversal, but has an automatic characteristic obtained by the iniiuence of centrifugal force. With'this latter arrangement the pre-selection vmay be dispensed with. l

' The device .ofy this invention generallymey be termed a.' transmission, although it may be used in' an automotive vehicle in conjunction with the already existing: gear change transmission, and though the device itselfembodies no gearing. Then, too, the invention is not limited to 'use on vehicles.

Dinerent arrangements are shown in the accompanying drawings for carrying out themvention.

Fig. 1 is a general view illustrating an engine with the usual clutch housing and transmission 'A Fig. 3 is a cross sectional view taken substan-A tially on line 3--3 of Fig. 2.

Fig. 4 is a cross sectional view taken substantially on line 4 4 of Fig. 2 showing some of the control elements.

Fig. 5 is a cross sectional view taken substantially on line 5-5 of Fig. 2.

controlling dental engagement of some of the Fig. "l isa view similar to Fig. 2 showing the gearing conditioned for a direct drive.

Fig. 8 is a view similar to Fig. 1 showing the gearing conditioned for a drive other than direct. Fig. 9 is a sectional view showing a different form of the invention and which embodies a centrifugal control.

Fig. 10 is a view similar to Fig. 9 showing the centrifugal elements eective.`

Fig. 1l is a sectional view taken substantially online lI-il ofFig.9.

Fig. 12 is a lay-out illustrating abutment teeth used in the centrlfugally controlled form.

Fig. 13 is a view similar to Fig. 12 showing the abutment teeth out of abutment relation.

Fig. 14 is a sectional view illustrating another arrangementfof the invention.

Fig. 15 is a sectional view taken substantially on line lB-IB of Fig. 14.

Fig. 16 is a'sectional view taken onlineI6- I6ofFig.9.

Fig. 16A is a fragmentary elevational view of the s'un gear sleeve shown in Fig. 14.

Fig. 17 is a cross-sectional view illustrating a modied form which involves no gearing.

Fig. 1B is a sectional view takensubstantially on line IB-IB of Fig. 17 showing some of the controlling elements.

Fig. 19 is a cross sectional view taken substantially on line IB-Ilv of Flg.,17 showing the oneway clutching arrangement.

Fig. 20 is a sectional view taken substantially on line 2li- 10 of Fig. 17 showing certain structural features.

substantially Fig. 22 is a cross sectional view similar to Fig. 19 but showing the parts in a different relation.

22,761 Fig. s is a. lay-out showing abutment teem for member 1| in the form of a ,collar on the sleeve ill and having teeth 22 and 23 for a dental engagement respectively with teeth iB and I 9. The oontrol member also has. extending elements constituting abutment teeth 24 and 25.

Y as shownl in Fig.'4 for the reception of rollers 32,

Fig. 23 is a view illustrating lan arrangement for pre-selecting a load on the control element.

Fig. 24 is a view illustrating the over-center spring arrangement of Fig. 23. p

For the purpose of illustrating an environment in which this invention may be employed, an in-v ternal combustion engine is illustrated at I in Fig. l having the usual bell housing 2 for a clutch, a transmission housing I andan auxiliaryhousing 4 within which may be Acontained the gearing of thtespresent invention. A driven shaft is shown The gearing is generally illustrated in Fig. 2. a v

driving shaft or element being illustrated at 6 and having an internal gear member 1. The driven shaft may be pilotedin the driving member 6 as illustrated at l. Surrounding the driven shaft for free rotation thereon is a sleeve.ll| having a so-called sun gear thereon, as shown at Il. The sleeve is provided with helical splines i2 the pur-` pose of which will presently appear.

A carrier I3 is connected in driving relationship with the driven shaft as by 'means of splines I4, and it has an auxiliary part Il. Between the two parts la and i5 are disposed a suitable number of planetary gears or pinions I l mounted on studs l1 and the teeth of which engage with Y l those ofthe gear members 1 and I l. I

The member II has an extending part equipped with teeth II for dental engaging purposes.v Secured to a iixed part of a housing or the like is a fixed reaction member 2li having teeth I9 also for dental engagement purposes. Mounted upon the helical splines is a .shiftable coupler or control each acted upon by a spring 33. The recesses are 'shaped so that lthe rollers are wedged between the bottom of the recesses-and the adjacent circumscribing surface on the carrier member l5, thus forming a one-way drive connection. The

rollers are confined between washers secured to the clutch ring` as by means of rivets 34.

The clutch ring 3U, however, is operably associated with the sun gear through the means of an arrangement which permits of a limited relative rotary movement. To this end the sun gear and clutch ring have circumferential recesses which match each other, and in the resultant chamber are coil springs 35. One of the washers which is attached to a clutch ring is notched or cut away to form shoulders 36 for confining the springs at one end, while studs 31, carried by the sun gear, abut the opposite ends of the springs. f When the springs expand as shown in Fig. 4, the studs 31 may abut the shoulders 38 on the washer, but the washer, and therefore the clutch ring, as shown in Fig. 4, can shift clockwise relative to the sun gear, or the sun gear may shift counter-clockwise relative to the washer and clutch ring by the flexing of the springs. This movement. of course, is limited. The normal position of the parts is with the springs extended, as shown in Fig. 4. The clutch ring 30 has an extending part which projects towardithe control member 2l 'and which structure as the rollers 32 shown in Fig. 4. Fixed to the sun gear sleeve non-rotatably is a member 44 and between the ring 42 and member 44 is a spring and stud arrangement thev same as the spring 32 and stud arrangement 31 and washer arrangement `Slishown in Fig. 4. 'I'he brake ring .42 has an abutment tooth arrangement I! for Ation made by the operator.

cooperating withthe teeth 25 on'the collar 1|. the same as is illustrated inFig. 6.

In thefarrangement shown in Figs. 2, 'I and 8, the gearing may be controlled by a pre-selec- To this end, a shifter fork 46 (Fig. 23) engages in the groovein collar Il. The fork is s iidably mounted as shown and is shifted by an arm 41, which is rockably mountedwith an arm 48. A spring 49 is connected to the arm 48 as at 50 and to a control arm 5| as at 52. An operable'control such as a Bowden wire or the like may be connected to the arm as at 53. The arm 5I may be shifted at will to posi- .tion the point of connection 52 to one side or the as follows: When the teeth Il and 22 of the carrier and the control collar are in dental engagement as shown in Fig. 7, theV drivingl member 1, the carriers i3 and I5, the collar 2l and the llower than that of the driving shaft, inasmuch as the carrier revolves with the planetary pinions rumiing around the sun gear. In lthis particular form, the helical splines I2 are of a right hand nature as shown in Fig. 2, this, however, depending upon the normal direction of rotation.

In considering now the making of a shift from low gear, which is the Fig. 8 position, to high gear, the Fig. 7 position', having in mind that the terms low and high are used to merely denote the relative arrangement: The driving member turns in the direction indicated by the arrow in Fig, 3, namely, counter-clockwise, as this figure is viewed, and the tendency at this time is for the sun gear to rotate in the opposite direction, namely, clockwise. The helical splines |2, therefore, tend to feed the collar 2| to the right. Therefore, the tendency is, in low gear when torqueis coming from the driving member, to maintain the dental engagement of the control collar with the fixed reaction member. At this time the pre-selection mechanism may be positioned so that the spring 49 also places a force however, may continue its acceleration beyond the speed of rotation of the carrier, which it may dorbecause of the studs 31 shifting counter-clockwise relative to the vother parts shown in Fig'. 4,

on the collar 2|, tending to maintain the dental engagement with the fixed reaction member. Suppose now that the engine is driving the4 vehicle with torque being delivered from the engine: The operator may shift the control arm 5| so that the spring tends to shift the control collar 2| to the left. The tendency is to disengage the collar from the fixed lreaction member. But this will not [occur so long as the torque is from the driving member tothe driven member.

-As the throttle of the engine is relieved, however,

the engine and the driving member tend to decelerate, but the carrier continues to rotate with the driven member or vehicle. Therefore, the torque is reversed. Upon such reversal the tendency of the sun gear is to startv to rotate with the driven member or counter-clockwise as Fig. 3 is viewed. The helical splines, together with the forces of the spring, substantially at the movement of the reversal, shift they control member out of dental engagement with the iixed reaction member, or in other words, from the Fig. 8 position to the Fig. '2 position. At this neutral position the teeth 24 on the collar strike the ends thus compressing the springs 35. Thus the sun gear. together with the collar, has a rotary movement relative to the ring 30, and accordingly, the teeth 24 rock or rotate relative to the teeth l0 on the ring until they can ride past each other or out oi' a blocking position. As soon as this happens the forces on the collar which come from the spring andthe helical splines I2 shift the collar further. to the left or from the neutral position of Fig'. y2 to the position shown in Fig. '1, thus causing a. dentalv engagement of the teeth between the collar and the planetary gear carrier. Accordingly, it will be noted that this dental engagement is effected substantially at the time of synchronization of thecarrier and the sun gear. engagement without clashing of the teeth.

Now, when the torque is again reversed by opening the engine throttle, the parts are tied together so that the relationship :between the driving and driven members is 1 to 1. With the torque coming from the driving member at this f pressure is required toimaintain dental engagement of the parts even though the thrust forces induced by the helix angle of the splines tend to cause a separation of the dental teeth.`

Reverting again to the Fig. 8 position or low gear: If the pre-selector is positioned so that the spring places a load on the collar which is to the right, thus tending to maintain the dental engagement with the fixed reaction member, a. reversal of torque will not cause a change of the gearing as above described. Such reversal causes oi the teeth 4|) on the clutch ring 3|) as shown in I Fig. l6 so that movement of the collar is interrupted. At this time. with the driving member decelerating and the carrier and driven member' continuing to rotate substantiallyI uniformlyor with slight deceleration, the sun gear, having been released from the iixed reaction member, accelerates from zero speed, and it will `come up to a speed which synchronizes with that of the xcarrier, and then will tend to rotate faster than the helical teeth to tend to feed the collar to the left, or out of dental engagement with the fixed reaction member, but the spring prevents this.

Now considering again Fig. '1: With the torque greater the torque the greater the tendency oi.

the splines to shift 'the collar to the right, but

also the greater the load. Very light torque resuits in a very light shifting tendency, with the result that the dental engagement with the car; rier is maintained. If, however. it is desired to eiect a change ofV gearing, the operator may swing the control so that the over-center spring tends to shift the collar tothe right. This causes the collar to shift from the Fig..7 position to the 2 position. At this time, with the engine and driving shaft decelerating and the carrier moving with the driven shaft, the sun gear is decelerating. The movement 'of the collar to the right, however, is stopped by' reason of the end to end engagement of the teeth 25 and Il. The

' forces delivered to the. sunv gear through the planetary gears tends to cause the sun gear to As a-result there is a nicety of dental slow down and approach rzero speed and tend to run in a negative direction. The brake ring l2 which normally moves with the sun gear, is

ultimately to the Fig. ll position. 'I'he torque,-

when coming from the driving member, tends to shift the collar to the right. It will therefore be seen that the collar is given a dental engagement with the fixed reaction member substantially when these two parts are synchronized, or

' in other words. when the collar, and therefore the sun gear. are substantially at aero speed. The parts are now in low gear and will remain therein until a pre-selection is made by shifting the spring so that it exerts forces on the collar, tending to shift it to the left.

Briefly reiterating, when the torque is from the "driving member, the helical splines ten'd to shift the collar Il4 to the right. and when the torque is reversed the helical splines tend to shift the collar to the left. Accordingly, with torque being delivered from the driving member the collar tends to accept dental engagement with the xed reaction member and tends to reject dental en. gagement with the carrier. With the pre-selector spring set-to oppose the rejection from the carrier, the dental engagement in Fig. 7 will be their cerner, the clutch ring, and auch mumA parts as are related thereto. The driven member is shown at I5 and to'which 'the carrier l3'-l5' is secured. The sun gear has a sleeve with right hand helical splines I2' disposed over the extending shaft of the driven member, and

ithasaring 5l amxedtooneend. Thenxedreaction member takes the form of a -ring 52 secured to a suitable part offs, housing or the like 5I. and .between the ring 5I and ring 52 is a oneway brake structure residing in rollers 5l which prevents the sun gear from rotating backwar or in a. negative direction.

The coupler collar 55 has teeth 55 for dental engagementfor the teeth i8 of the carrier. 'I'his control collar is mounted on the helical splines. In this form the control collar and the clutch ring 50 have abutment teeth as illustrated in the lay-out views, Figs. 12 and 13. The teeth on the collar are shown at 5l and those on the clutch ring at 51, and they have angular or inclined ends as illustrated. e

The control collar includes a centrifugal arrangement residing in s, housing comprising a maintained. When the pre-selector spring is set to aid the rejecting action, the collar will shift to the Fig. 2 position; then the sun gear will decelerated, and when it approximates zero speed and tends to' run negative, the blocking teeth beand collar now accelerate. andas the collar tends to overrun theA carrier the blocking teeth become disaligned and the movement to the left continues and the dental engagement with the carrier is LY-is blocked'by the abutment teeth. The sun gear ber.

established substantially when the collar and carrer are synchronized. Thus the structure effects a change from a low gear ratio to a highv -gear ratio, or vice versa, without breaking the power line as by means of a clutch or the like. The blocking teeth 24 and 40, and 25 and 45, may be so arranged that the blocking discontinues when the corresponding teeth for dental engage-v ment,v namely, Il and 22 on the one hand and I9 and 23 on the other hand, are in position for a proper dental engagement.

In Figs. 9 to 13, inclusive, an arrangement is shown wherein some of the control is effected by centrifugal force. In this form many of the parts are the same as those parts previously described, and in orde'r to avoid duplicate description these parts are given the same reference characters with a prime mark. These parts are the driving member, the sunl gear, the planetary gears and part 50 secured to the collar as-shown. and a part Bi keyed to rotate with the part SII. but relatively axially movable. Within the housing are centrifugal weights which may take the form of segments 52 held radially inwardly by a circumscribing coil spring 63. Each weight has a bumper or buffer of rubber or the like 84, and between the weights and the housing members are roller elements such as balls 65 confined in facing recesses constituting pockets, the recesses being shown at 86. The housing member 5l is prevented from shift to the right as it butts up against the member 5I in turn held by a suitable ring, and the housing member 60 and the control'col-v lar are shiftable.

The operation of this form of the invention is as follows, this form beingresponsive both to the torque reversal and to speed of rotation: With the parts in the position shown in Fig. 9 the .drive is transmitted from the driving member to the driven member through the gearing. The driving member is revolving, the sim gear is held from negative rotation or backward rotation by the overrunnlng brake rollers 5I. The carrier is revolving around Ithe sun gear at a speed lower than that of the driving member. Upon reversal of torque, as by closingv the engine throttle, the driving member begins to decelerate while the carrier continues to rotate with the driven memy This causes the sun gear to accelerate from zero. When the torque is from the driven mem`- ber the helical splines tend to shift the controlling member 55 to the left, and this tendency, or the centrifugal action, or both, places an axial load to the lei'ton this member. However, the

abutment teeth come into engagement, as indi'- cated in Fig. 12, to prevent dental engagement between 'i land 56. As the control member tends' l to overrun the ring 50', the studs 31' (see Fig. 4)

`compress the springs 35.' 'as the rollers I2' preyvent the clutch ring from rotating faster than and so long as the speed of rotation is adequately high the parts will remain in this high gear relationship. The helical splines tend to disengage the dental engagement at i8 and 56, but this is prevented by the centrifugal force and the load on the parts. A high torque places a high load on the parts. A low torque places a low load on the parts. When the R. P. M. becomes sufficiently low that the centrifugal weights do not exert enough force to maintain the dental engagement shown in Fig. 10, the control member shifts automatically out of dental engagement with the carrier and the sun gear becomes locked against negative rotation relative to the xed reaction member, and the parts are then in low gear relationship, as shown in Fig. 9. Thus the parts will shift from high gear relationship to low gear relationship at a relatively high R. P. M. under high torque, but will not shift from high gear relationship to low gear relationship under low torque until a relatively low R.. P. M. is attained. Thus while a reversal of torque is necessary to eiect a shift from low gear relationship to high gear relationship, the high gear relationship will maintain until the conditions of'torque and speed require a shift back to low gear relationship. The reason for the inclined ends on the abutment teeth 58 and 51 is to assure a sepatakes place incident to the release of the com-- pression on the springs 35. 'The inclined faces of the abutment teeth strike each other and the collar is cammed or given a push, so to speak, away from the carrier.

Fig. 14 shows an over-drive arrangement where, in one condition, the parts are in a 1 to 1 relationship and in another the driven member is rotated faster than the driving member. Also, this form shows the centrifugal control. In this form the driving member is at 10, the' driven member in the form of an internal gear is at 1I, a fixed reaction member is at 12 having teeth 13, the sun gear and its sleeve are illustrated at 14, while the carrier forthe planetary pinions is shown at 16, the carrier being splined as at 11 to the driving member.

A coupler collar 18 has teeth 18 and an antil friction bearing 80 is between housing member 8| of the centrifugal unitvand the collar. The housing member 8| is slidably fastened to a housing member 82 which may be mounted upon the pinion studs 83 to rotate with the carrier and driving member. A `ring 84 also rotates with the driving member, and between this ring and the sun gear is a one-way clutch which may residel in overrunning clutch rollers 85, which prevents the sun gear from overrunning the carrier.

Within the housing 8I-82 are centrifugal weights 86 which may be like those previously described normally retrained inwardly by a coil spring 81 and operating on balls and recesses 89 to spread the housing. The antifriction bearing 80 takes care of the relative rotation betwe'en the carrier and the sunlgear. l

Keyed to one end of the'sun gear sleeve is a member 9U associated with a brake ring 9i through the means of coil springs 92 and abutments in theform of studs 83 on the member 98 and abutments 9i cut out of a washer 95 on. the brake ring. Between'the brake ring and the xed reaction member 12 is an overrunning brake comration of the teeth I8 andl 56 when a shift is made from high to low gear relationship.- As the j establishingof a dental connection incident to Y prising rollers 9B. The brake ring 9| and the control member 18 have cooperating abutment teeth 91 and 98 corresponding to the abutment teeth 58 and 51 as shown in Figs. 12 and 13.

The splineson the sun gear upon which the control member 18 is mounted are such that when the torque is from the driving member the tendency is to shift the control member to the right to disengage the dental connection. To this end the helical splines are of a left hand nature as shown at 99 in Fig. 16A.

This arrangement operates as follows: With the parts in the lposition shown in Fig. 14, theI drive is a directl to 1 ratio. The carrier and planetary gears rotate with the drive shaft 18 and the load on. the lsun gear tendsto cause it to overrun the carrier which is prevented bythe overrunning clutch members 85. Therefore, the driven member1l is caused to rotate in a 1 to'l ratio with the driving member. This continues with torque-delivered from the driving member until the speed of rotation reaches a point where the centrifugal force tends to cause the weights to shift outwardly, but the abutment teeth prevent this action as they are in abutting relationship. vUpon torque reversal so that the driveV .comes from the driven member, and with the carrier and driving member decelerating, the sun -they may interengage with each other and the centrifugal weights then vurge the control member 18 to the left to establish the dental engagement with the iixed reaction member 12. Again this occurs when the control collar is substantially synchronized with the reaction member, or in other words when it is substantially at zero speed. Under these conditions the sun gear is held locked against rotation, and the driving member may now drive the driven member through the gearing, with the driven member rotating faster than the driving member. This condition will maintain until torque and speed are such that a change of gearing may be made. The tendency is for the splines 99 to expel the control member 18 from dental engagement with the xed reaction member. As long as the centrifugal force resists this expelling tendency,l the parts will remain in the over-drive relationship. At high -torque, the change is made at a higher R. P. M. than at low torque, because the lower the torque the lower the centrifugal force needed to maintain the dental engagement. When the dental engagement is broken, the sun gear tends to pick up speed but is prevented from overrunning the carrier by the overrunning clutch rollers 85, with the result that` there is an arrangement for-the breaking or the reversal of torque independently of the existence of gearing. In this form the driving member |88 is shown as having an element IUI with teeth i 02. A driven member |83 may be an element which extends into a case IM of a gear change transmission, and in fact the member |03 may be one of the elements in such gear change transmission.

The driven member |03 is provided with helical splines I UI which are of a right hand nature, as

6 saver illustrated, where the direction -of rotation, as operated to permit uld pressure to enter the Figs. 18 to 20 are viewed, is clockwise. chamber |08, a load to the left is placed on part As a means facilitating the control of this ar- ||4, but .this load is not sufficient to cause any rangement there may be an annular piston action as long as the torque is being delivered. slidably mounted on an extension of the transmis- 5 from the driving member. Upon torque reversal, sion case, thus forming an annular chamber |08 however, which would take place when the throttle to which a pressure line |01 connects. A control of the vehicle engine is closed or partially closed, Vvalve |08 is arranged to connect the line |01 the driven member |03 starts to drive member either to a pressure line |09 or an exhaust line I |4 and the helical splines tend to shift the memdepending upon the positions of the control 10 ber |4 to the left, and this action, with the supvalve. In an automotive vehicle the line |09 may Diemeliial action of the iiid Pressure. GaiiSeS the connect to the pressure lubricating system of the member ||4 to shift to that position Shown in'FiE- engine while the line ||0 may lead back to the 17 so that the teeth ||5 and |02 are disengaged. sump, and the valve may be mounted upon the At this moment the relative positions of the hub floor or toeboards ||2 oi' the vehicle. When the 16 element |2.I and the ring element |22 may be Subvalve is pushed down in the position indicated, oil stantially aS illustrated in Fig. 22. 01' in other under pressure enters the chamber |00, and when 'words with the ring element rotated somewhat the valve is permitted to shift back by its spring clockwise relative to the hub element. in which H3. the line |01 is connected to the relief line H0. condition the springs |34 are stressed. As soon A driven coupler element ||4 has teeth H5 and zo as the driving element IDI. in its deceleration. it is mounted upon the helical splines and is acted releases the lrrlp across the rollers |24. the springs upon by a spring |I0, while the piston functions |34 cause the ring element |22 to shift rotatably on the driven dement through the means of a relative to the hub element, or from the Fig. 22 thrust bearing I1. The piston may be held fro position to the Fig. 19 position. Just prior to this rotation by one or more ping |20- g5 shift, however. the abutment hooks |4| are posi- A' hub-like element 12| is' non-rotatably contioned to the left so that they lie along side the nected to the driven member |03 as by means of abutment teeth |40 on the clutch ring. eS Shown splines as shown in Fig. 19, while a ring f|122 which in Fig. 22, and as illustrated in dotted lines in Fig. may be called a clutch ring has a loose connection 21. Thus the springs in IOekini the ring |22 with the hub |2| as by means of loose splines as 30 counterclockwise as 118.19 iswlewed. i$931569 the shown at |23 in Fig. 19. .The clutch ring is teeth |40 to engage behind the abutment teeth I4| formed with recesses to receive overrunning clutch as shown in full lines in Fig. 21. Accordingly. rollers |24. These rollers are mounted in a cage the driving member may decelerate or come or retainer |25, which isprovided with axially to rest While the driven element |03 may rotate extendingv abutments |28. Thel cage is also proa5 faster or overrun the'same. This condition will vided with openings |21 through which extend exist even in the absence of iiuid pressure because abutments |28 on the ring |22, s of the engagement of the abutment teeth which A spring retainer |30 is non-rotatably secured hold the member Ill to the left With the Spring to'l the driven member |03 and the several parts lll flexed.

are held assembled by a snap ling |3|. In fact 40 However, when the torque is reversed and the the spring H8 reacts through l washer |32A driving element is accelerating. it nrst comes up through the hub-like element |2f ind eventually substantially to the speed of the rotation of the to the holding ring |3l. The getainer |30- 1s clutch ring |22 and the overrunning clutch memprovided with nxed partitions or 'abutments |22, bers take hold. The ring |22 i8. therefore. rotated and positioned between each abutment and the 4.5 clockwise relative to the hub element or from the abutments |28 on the clutch ring are springs POSiiOnin Fig.A 19 to the POSIOD of the type aS |34. Also positioned between the abutments |32 illustrated in Fig. 22, and this releases the abutandV the abutments |26 on 'the roller cage are ment teeth so that the Spring ||0 shifts the elesprings |35. ment ||4 u) the right for a dental engagement at Itwillbe readily appreciated from a considera- |02-'l l5. This. 0i course. occurs only when the s tion of Figs. 18 and 19 that the springs |34, confluid pressure is relieved. In the clockwise movesidering the parts at rest, tend to urge the clutch ment 0f the ring |22 relative |50 it hub. the ring counter-clockwise, or in other words reverse springs`|34 are again compressed and maintained to the 'direction of rotation of the parts during compressed at all times of the locked up condioperation. It will also be seen that the springs, tion. 0r in other Words. 8. dentel eneement et |32, which may be quitelight. urge the roller re- |02| Il.' It will be observed that the dental'entainer in a clockwise direction, or in other words', gagement at |02| Il occurs substantially at the in a `direction which tends to cause the rollers to time'of synchronization of the driving and driven wedge into driving engagement between the 'drivmembers. Thus the teeth slide quietly into ening member 0| and the clutch ring |22. o0 sagement. The amount of rotation of the ring. The clutch ring |22 is provided with lugs' |40 |22 relative to the hub |2|, and therefore the which project therefrom, while the driven element member Ill. i8 Preferably Such that there iS e' ||4 is provided with hook-like elements i4|.i possibility of a dental engagement'at |02||I at These luga and hook-like elements constitu A several different points. or in other words, be abutment teeth. 05 tween several sets of teeth. Therefore. if for al! The operation o: this structure is as follows: reason the dental engagement for the nrstpo'xi- The normal condition whentho parts are coupled tionl is passed the second or subsequent third 4forl driving is with the teeth |02and il! in dental positions oi dental engagement will become enecengagement. They spring ||3 urges the member tive. Accordingly, the dental engagement is dis- ||4 to the right as'Fig. 17 is viewed. The drive 7 0 established substantiallyasthepartsare synchrois then'from the member |I| through member nized upon torque reversal, and the dental en- HLto JI lllgg'l'he right hand helical splines also sagement is established substantially as the partsV place a load to the right on'the member H4. are synchronised upon tortillev reversal. Upon torque reversal the parts remain in This arrangement 'may be used in a vehiclo'for looked position. 1i, however. the valve ||3 76 the changing of the gearsina gear change transmission. By depressing thev valve to the position indicated and decelerating the engine, the driven member |03 is freed and the gears in the transmission IM may be changed. In an intermediate gear, the operator may hold the valve in the position shown and the engine accelerated to drive the vehicle in such intermediate gear, and in this case the fluid pressure prevents the dental engagement. The drive, however, is then through the overrunning rollers |24 through the clutch ring |22, hub member |2l, to the driven member |03. Thus an operator may go through the entire range of gear changes whileholding the parts in the freewheeling position, due to the position of the valve, and then finally when high gear is attained relieve the valve for the dental 4engagement and the direct locked up drive.

I claim:

1. In a torquev transmitting device, driving and driven members and toothed parts arranged to be brought into and out of dental engagement, means tending to shift one of the parts for `such dental engagement substantially upon reversal of torque, said one part being rotatable, a ring mounted for oscillation relative to the shiftable toothed part, abutment teeth on the ring arranged to block the movement of said part and prevent dental engagement, and lmeans operable bythe other of the said toothed parts substantially as the two toothed parts come into synchronization for rocking the Iring to shift the abutment teeth out of blocking position.

2. In a torque transmitting device, driving and driven members and toothed parts arranged to be brought into and out of dental engagement, means tending to shift one of the parts for such dental engagement substantiallyLupon reversal oi' torque, said one -part being rotatable, a ring mounted for oscillation relative to the shiftable toothed part, abutment teeth on the ring arranged to block the movement of said part and prevent dental'engagement, said ring being arranged to be operated rotatably relative to the shiftable toothed part by the other one of the said toothed parts substantially when the two toothed members come into synchronization to shift the abutment teeth out of blocking position for dental engagement.

3. In a torque transmitting device, driving and driven members andtoothed parts arranged to be brought into and out of dental engagement, means operable incident to torque reversal tending t `shift one of the toothed parts into dental engagement with the other, said one toothed part being rotatable, said shiftable toothed part having abutment teeth thereon, an element `having abutment teeth thereon normally rotatable with said one part and positioned so that the abutmentY teeth are substantially engageable to prevent dental engagement, and means 4operable by the other one of said toothed parts substantially when the two toothed parts come into synchronization to shift the element and disengage the abutment teeth.

4. In a torque transmitting device, driving and driven members and toothed parts arranged to be brought into and out of dental engagement, means operable incident to torque' reversal tending to shift one of the toothed parts into dental engagement with the other, an element mounted on and for oscillation relative to the shiftable toothed part, the shiftable toothed part and said element having abutment teeth, spring means normally holding the element so that the abutment `teeth strike each other to prevent dental engagement, and means operable by the other one of said toothed parts substantially ,ipon

the synchronization'of the two toothed parts to os-cillate said element relative to the shiftable toothed part for dental engagement substantially at such synchronization.

5. In a transmission, rotatable driving and driven members, gearing means including a rotatable part, reaction means, a shiftable and rotatable control member arranged to have a dental engagement with the gearingmeans in one posi.-

tion and a dental engagement with the reaction means in another position to establish different ratios between the driving and driven members, means operable to shift the control member from one position to another incident to torque reversal, means for blocking the shift .short of dental engagement, and means operable by the part about to be dentally engaged for rendering the blocking means ineiective substantially when the parts to be dentally engaged become synchronized.

6. In a` transmission, rotatable driving and driven members, gearing means including a rotatable part, reaction means, a shiftable and rotatable control member arran'ged to have a dental engagement with the gearing means in one posi- `tion anda dental engagement with the reaction means in another position to establish different ratios between the driving and driven members, means operable at will to place a load upon the control member and operable to aid in the shift of the control member incident to reversal of torquato disengage one dental connection and to establish another, means rotatablewith the control member for blockingthe shift of the control `member in an intermediate non-engaged position, and means operable by the part about to be engaged for shifting the blocking means out of blocking position substantially when the control member and the. portion to be dentally engaged therewith are substantially synchronized.

7. In a transmission, rotatable driving and driven members, gearing means including a rotatable part, a iixed reaction means, a control element shiftable upon helical splines on one of the gearing means, said control element being arranged to have a dental'engagement with the reaction means in one position and with a gearing part in another position to establish diii'erent ratios between the driving and driven members, means operable incident to torque reversal to shift l the control element, a ring element mounted for oscillation relative to the control element and having abutment teeth for stopping the shift of the control element in a position of no dental engagement, and means for shifting the ring element substantially when the control element and the part to be dentally engaged therewith come into synchronism.

8. In a transmission, rotatable driving and driven members, gearing means including a rotatable part, a xed reaction means, a control element shiftable upon helical splines on one of the gearing means, said controlelement being arranged t0 have a dental engagement with the reaction means in one position and with a gearing part in another position to establish different ratios between the driving and driven members, means operable incident to torque reversal to shift the control element, said means including a control device operable at will, a ring element mounted for oscillation relative to the control element and having abutment teeth-for stopping the shift4 of the control element in a position of no engagement, 'and means for shifting the ring element substantially when the control element and the part to be dentally engaged therewith come intosynchronization.

9. 'In a transmission, rotatable driving and driven members, gearing means including a rotatable part, a. fixed reaction means, a control element, shiftable upon helical splines on one of the gearing means, said control element being arranged to -h`ave a dental engagement with the reaction means in one position and with a gear- 'stantially when the control element and the part to be dentally engaged therewith come chronization.

10. In a transmission, driving and driven meminto synbers and planetary type gearing including a sun.

gear, a fixed reactionmeans, one-way clutching arrangement between the sun gear oi the gearing iixed reaction member, a control member slidand,` arranged toshift out of blocking position substantially when the control' member is at zero 14. In a transmission, a. driving member having teeth, a driven member having helical splines, an intermediate member mounted on the splines and having teeth. for dental engagement with the driving member, means for applying an axial load on the intermediate member tending to break the dental engagement and operable to so break the dental engagement when torque reverses so and the fixed reaction means, a control member slidably keyed to the sun gear by inclined means arranged kto tend to shift the control member upon torque reversal, teeth on the control niember and a gearing lelement for locking the gearing against movement when dentally engaged and for mission of the torque through the gearing," and centrifugal means for controlling the shift of the control member toward `dental engaging position in accordance with the speed 'of rotation.

11. In a transmission, driving and driven members and planetary type gearing including a sun gear, a ilxed reaction means, a one-way clutch'- ing arrangement between the sun gear of the gearing and the xed reaction means, a, control member slidably keyed to the sun gear by inclined means arranged to tend to shift `the control member upon torque reversal, teeth on the control member and a gearing element for locking the gearing against movement when dentally engaged and for releasing the gearing when disengaged become synchronized to discontinue the blocking action. V

12. In a transmission, driving and driven mem- .bers and planetary type gearing includinga sun gear, a one-way clutch arrangement between the sungear and anotherelement of the gearing, a tlxed reaction member, a control member slidably mounted onh'elical devices on the sun gear which tend to shiit the control member incident.

to reversal of torque, teeth on the control memreleasing the gearing when disenaged for transy that it is delivered from .th'e driven member to the driving member, means for holding the intermediate member4 dentally disengaged while-the driving member operates at a lower R. P. M. than the driven member, and means operable by the driving member for releasing the holding action substantially as the driving member comes yup to the speed of rotation of the driven member to reestablish' the dental engagement. l 15. In a transmission, a. driving member havin teeth, a driven member having helical splines,l an intermediate member mounted on the splines and having teeth for dental engagement with the driving member for the transmission of torque from the driving member to the driven member..

means for applying an axial load on the intermediate member` tending to shift the driven member out of dental engagement, and operable substantially upon torque reversal to aid in the shifting of the intermediate member to break the dental'engagement, means operable as the driving member decelerates relative to the driven member to hold the intermediate member in dental disengaging position, and operable by the driving member to release said holding when thedriving member, upon increase oi' R. P. M., substantially synchronizes with the driven member and intermediate member. y

16. In a transmission, a driving member having teeth, a driven member having helical splines,

ber and reaction means arranged for a'. dental engagement and centrifugal means arranged to apply shifting forces on the control member toward dental engagement in accordance lwith the speed or rotation. Y

13. In a transmission, driving and driven memi bers and planetary me gearing including a'sun gear, a, one-way clutch arrangement between the sun gear and another element o! the gearing, a

. ber, said last mentioned means comprising a ring oscillating' on the driven member and having a dentalengagement, means operable as the driv in g member decelerates relative 'to the driven member to hold the intermediate member in cien--4 tal disengaging position, and operable to release said holding wh'en\the driving member, upon in crease of R. P. M., substantially synchronizes'- withthe driven member and intermediate memone-way clutch arrangement with thedriving member, and interengaging lugs on the intermediate memberand said ring.

1'7. In a tron, a driving member having teeth, a driven member having helical splines, an intermediate member mounted onth'e splines and having teeth for dental engagement with the driving member for the transmission of torque :from the driving member to the driven memmember to hold the intermediate memberin dental disengaging position, and operable to release said holding when the driving member, upon increase of R. P. M., substantially synchronizes with the driven-member and intermediate member, said last mentioned means comprising a ring oscillatable on the driven member and having a one-way clutch arrangement with the driving member, and interengaging lugs on the intermediate member and said ring, spring loading means on the ring for shift of the ring to engage the lugs, said one-way clutch serving to shift the ring to disengage the lugs as the driving member tends to exceed the R. P. M. of the driven member.

18. In a torque transmitting device, a driving member, a' driven member, a shiftable coupling part, a connection between the coupling part andone member including an inclined plane, ythe coupling part and the other member having cooperating teeth arranged to be dentally engaged and `disengaged by Aaxialjmcfveinent of the coupling part alongthe inclined plane, the inclined plane placing v,a thruston the coupling part tending to maintain' dental engagement when the torque is vdelivered lfrom one member and placing a thrust on the coupling part tending to break the dental engagement when the torque is delivered from the other member, the angle of the inclined plane being such that the axial thrust on the coupling part under the` torque load in a direction tending to break `the dental engagement, is substantially balanced by the resistance to such movement of the coupling part due to the combined loads on the dentally engaged teeth and on the inclined plane,`and control means for placing an additional thrust on the coupling part for breaking the dental engagement when torque tends to break the dental engagement.

19. In a torque transmitting device, a driving 'member, a driven member, a shiftable coupling part, a helical spline connection between the coupling part and one member, the coupling part and the other member having cooperating teeth arranged to be dentally engaged and disengaged by axial movement by the coupling part along the helical splines, the'helical splines placing a thrust on the coupling part tending to maintain dental engagement; when a torque is delivered from one member and placing a thrust on the coupling part tending to break the dental engagement when the torque is delivered from the other member, the angle of the helical splines being such that the axial thrust on the coupling part under a torque load and in a direction tending to break the dental engagement is substantially balanced by the resistance to such movement o1 the coupling part, due to the combined loads on the dentally engaged teethand on the splines, and control means for placing an additional thrust on the coupling parts for breaking the dental engagement when the torque tends to break the dental engagement.

20. In a torque transmitting device, a driving member, a driven member, a shiftable coupling torque is delivered from the driving member-to the driven member and placing a thrust on the coupling part ina direction tending to break the dental engagement when the torque is delivered from the driven member to the driving member, the angle of the helical splines being such that the axial thrust on the coupling Dart, when under a torque load with the torque delivered from the driven member to the driving member, is substantially balanced bythe resistance to such movement of the coupling part due to the combined loads on the dentally engaged teeth andl on the splines, control means for placing an additional thrust on the coupling part for breaking the dental connection when the torque is delivered from the driven member to the driving member, means for blocking the coupling part in dent-ally disengaged position when the driving member is operating at R. P. Mls lower than that of the driven member and means operable upon acceleration of the driving member and when the driving member tends to overrun the driven member to release the blocking means -for shift of the coupling part into dental engagementwith the teeth of said other member.

21. In a torque transmitting device, a driving member, a driven member, a coupling part, one of the members and the' coupling part having teeth-for dental engagement, the other member and the coupling part being splined together so that the coupling part may shift axially relative thereto, means operable to place a thrust on the coupling part and shiftl the same axially to disengage the teeth, a. blocking element, the element and the coupling part having blocker teeth arranged for inter-engagement, means mounting the blocking element for normal rotation with the coupling member and in a position so that the blocking teeth engage and hold the coupling part out of dental engaged position, said blocking ele ment being rockable relative to the coupling part,

an over-running clutch device between the member having the dentaly engaging teeth and the blocking element and effective to grip and shift the blocking element out of blocking position4 when the R. P. M. of the member with the dental engaging teeth substantially synchronizes with the'R. P. M. of the coupling part.

ment, means tending to shift the coupling partv toward dental engaged position, control means operable to shift the coupling part to dis-establish the dental engagement to thereby uncouple the driving and driven members, a blocking element, means mounting the blocking element f or' rotation normally with the coupling part and for rocking action relative to the coupling part, the blocking element and the coupling part having inter-engaging blocking teeth, an over-running clutch between the blocking element and the driving member operable to release the blocking ber to an R. P. M. below that of the coupling part when the dental engagement is dis-established A to effect an engagement .oi the blocking teeth element and rock the same relative to the coupling part when the R. P. M. of the driving member tends to exceed that of the coupling part for rie-establishment of the dental arrangement between the'drving member and the coupling part.

423. In a torque transmitting device, a driving member, a driven member, a coupling part having a spline connection with one member along which the coupling part is axially shftable, the coupling part and the other member having cooperating teeth arranged to be brought into and out of dental engagement by the axia1 shift of the coupling part, means including control means for placing an axial thrust on the coupling part, the spline connection and the dentally engaging teeth being angularly disposed helicaliy relative other whereby transmission of torque places ant0 each other whereby transmission of torque places an axial thrust' on'. the coupling part in a direction depending upon which member is delivering the torque, the relative angle being such that the thrust caused thereby in a direction which tends to break the dental engagement is insufficient to overcome the combined loads on the coupling part whereby. the teeth remain dentally engaged, the control means being operable to vary the axial thrust on the coupling part for axial shift thereof,.blocking means for-preventing the coupling part from shifting to cause an engagement of the cooperating teeth while the driving and driven members are rotating at diierent speeds, the blocking means being operable by one of the members for releasing the blocking action when the driving and driven members come-substantially into synchronization.

24. In a. transmission, rotary driving and driven members, rotary gear members for esdrivingratio between the driving and driven members, the said' means for slidably connecting the coupler on one of said members and the dentallyv engaging teeth being angularly vdisposed helically relativo to each other whereby transelement upon deceleration of the driving mem-A establishing another vconnection between the l driving and driven members at a different ratio.

25. In atransmission, rotary driving and driven lmembers, rotary gear members for establishing ldifferent driving ratios .between the driving and 'driven members, a coupler, means slidably and drivingly mounting the coupler on one of said members, dental teeth on the coupler, cooperating dental teeth adapted to engage with the teeth 'I on the coupler when the coupler is in one position of its sliding movement for the transmission of torque'and for establishing one driving ratio between the driving and driven members, the said means for slidably connecting the coupler on one of said members and the dentally engaging teeth being angularly disposed helically relative to each axial thrust on the coupler in a direction depending upon whether the torque is delivered from the driving member or the driven member, control means for placing an axial thrust on the coupler, the said relative angle lbeing such that the thrust caused thereby in a direction which tends to break the dental engagement is insufflcient to shift the coupler due to the combined loads on the coupler, whereby the teeth remain 'dentally engaged upon torque reversal, said control means being operable to vary the thrust on the coupler for axial. shift to break the dental engagement' when the thrust on the coupler incident to the transmission of torque is in a direction tending to break the dental engagement, means for establishing another connection between the driving and driven members at a dierent ratio, said control means being also operable to vary the axial thrust on the coupler for shift of the coupler toward dentally engaged position and blocking means for preventing the coupler from shifting to' dental engaged position` while` the coupler and the teeth to be dentally lengaged thereby are dis-synchronized, the blocking means being operable by one of the members for releasing the blocking action when the coupler and the teeth about to be dentally engaged thereby become substantially synchronized.

26. In a transmission, rotary driving and driven members, rotary gear members for establishing driving connections of different ratios be-4 tween the driving and driven members, a coupler. means slidably and drivingly mounting the coupler on one of the members, dental teeth on mission 0f mmm places animal thrust On'the 60 disposed helically relative to each other so that coupler in a direction depending upon' whether thetorque is delivered trom the driving member or kthe driven member, control meansl for placing an axial thrust on the coupler, the said rel.-

when torque is transmitted from the drivingmember an axial thrust is placed on the coupler tending to shift it toward dentally engaged position, and so that when there is a torque reversal ative' angle being such that the thrust caused oli-at the denmly engatmg teeth the axial thrust thereby 'in a direction which tends to break the dental engagement is insufllcient to shift the coupler dueto the combined loads on the coupler, whereby the teeth remain dentally enga'sed upon torque reversal. said control means for axial shift to break the dental engagement when the thrust on the coupler incident u the transmission of torque isv in a direction tending being operable to vary the thrust on the coupler .tends to shift the coupler out of dentally engaged to break the dental engagement. and means for engagement and means for establishing another connection between the drivingand driven members at a different ratio.

27. In a transmission, rotary driving and driven members, rotary gear members for establishing driving connections of diierent ratios between the driving and driven members, a coupler, means slidably and-drivingly mounting the coupler on one of the members, dental teeth on the coupler, cooperating dental teeth adapted to engage with the teeth on the coupler when the coupler is in one position of its sliding movement for the transmission of torque and for establishing one driving ratio between the driving and driven members, the said means for slidably mounting the coupler on one of said members and the dentally engaging teeth being angularly disposed helically relative to each. other so that when torque is transmitted from the driving member an axial thrust is placed on the coupler tending to shift it toward dentally engaged position, and so that when there is a torque reversal at the dentally engaging teeth the axial thrust tends to shift the coupler out of dentally engaged position, control means for placing an axial thrustl on the coupler, the relative angle being such that the thrust upon said torque reversal is insufficient to shift the coupler whereby the teeth remain dentally engaged, said control means being operable to vary the thrust on the coupler for axial shift upon torque reversal at thedentally engaging teeth to .break the dental engagement,

means for establishing another connection be sarei tween thedriving and driven members at a different ratio, said control means being also operable to vary the thrust on the coupler for shift of the coupler toward said dentally engaged position and blocking means for blocking movement of the coupler toward dentally engaged position while the coupler and the teeth to be dentallyengaged are dis-synchronized, the blocking means being operable by one of said members for releasing the blocking action when the said teeth become substantially synchronized.

28. In a transmission, rotary driving and driven members, rotary gear members for establishing diierent driving ratios between the driving and driven members, a coupler, means slidably and drivingly mounting the coupler on one of the members, dental teeth on the coupler, cooperating dental teeth adapted to engage with the teeth on the coupler when the coupler is in one position of its sliding movement for the transmission of torque and for establishing one driving ratio between the driving and driven members, the said means for slidably connecting the coupler on one -oi said members and the dentally engaging teeth being angularly disposed helically relative to each other vso that 'when torque is transmitted from the driving member there is an axial thrust on the coupler tending to shift it toward dentally engaged position and so that when there is a torque reversal at the dentally engaged teeth a thrust is placed on the coupler tending to shift it out of dental engaged position, control means for placing an axial `thrust on the coupler, the relative angle being such that the thrust on the coupler incident to said torque reversal is normally insufficient to overcome the combinedloads on the coupler whereby the teeth remain dentally engaged, said control means being operable to vary the thrust on the coupler for axial shift upon of the members, dental teeth on the coupler, co-

operating dental teeth adapted to engage with the teeth on the coupler when the coupler is in one -position of its sliding movement for the transmission of torque and for establishing one driving ratio between the driving and driven members, the said means for slidably connecting the coupler on one of said members and the dentally engaging teeth being angularly disposed helically relative to eachother so that when torque is transmitted from the driving member there is an axial thrust on the coupler tending ,to shift-it toward dentally engaged position and so that when there is a torque reversal at the dentally engagedteeth a thrust is placed on the coupler tending to shift it out of dental engaged position, control means for placing an axial'thrus't on the coupler, the relative angle being such that the thrust on the coupler incident to said torque reversal is normally insufficient to overcome the combined` loads on the coupler whereby the teeth remain dentally engaged, said control means being operable to vary the thrust on the coupler for axial shift upon torque reversal at the engaging teeth to break thedental engagement, means for establishing aconnection between the driving and driven members at a different ratio, said oontrol means being also operable to vary the thrust on the coupler for shift of the coupler toward said dental engaged position and blocking means for blocking movement of the coupler toward dental engaged position while the teeth about to be dentally engaged are dis-synchronized, the blocking means being loperable by one of the members for releasing the blocking action when the dentally engaging teeth become ,substantially synchronized.

ERNEST E. WEMP. 

